Water-cooled panel

ABSTRACT

A hollow panel through which cooling water flows comprises a rectangular box having one undulating surface that is exposed to heat, such as the heat of exhaust gases from a BOF converter.

United States Patent Mitchell et al. 1 May 9, 1972 [s41 WATER-COOLED PANEL [56] References Cltcd [72] Inventors: Hartman Mitchell; Joseph A. .Vletm'ls z, UNITED STATES PATENTS both of Pittsburgh, Pa. 3,197,186 7/ 1965 Mirigay ..266/15 Assign: pp p y he Pimhurgh' Pa. 3,347,539 10/1967 Mltchell et al.... ..266/35 [22] Filed: Oct. 27, 1970 Primary E.\'aminer-GeraId A. Dost Attorney-Sherman H. Barber, Oscar B. Brumback and Olin [21] Appl. No.: 84,343 E. Williams BS'IRA T [52] [1.5. CI 266/15, 266/35 [57] A C [s 1 1 Int. Cl ..C2lc 5/40 A hollow Panel through which wolifls Water comprises a 66 3| 2 35. 6 I rectangular box having one undulating surface that is exposed [58] new 0' send? 2 l 3 P s to heat, such as the heat of exhaust gases from a BOF' converter.

14 Claims, 5 Drawing Figures ri/ I PATENTEDMY 91912 sum 2 UF 2 FIG. 4

INVENTORS HART WAN MITCHELL fl' JOSEPH A. V/ETOR/il BYJ) BACKGROUND OF THE INVENTION The present invention relates to a basic oxygen furnace (BOF) and, more particularly, to an exhaust hood for receiving and conducting hot effluent discharge gases away from the BOF.

A conventional BOF steel plane comprises, among other things, a converter and a water-cooled exhaust gas hood located above the converter. The hood first receives and then conducts the hot exhaust gases away from the BOP to other apparatus which cleans and treats the gases.

Exhaust hoods of various types have been proposed in the prior art. Some have a plurality of fluid carrying tubes that are arranged in much the same fashion as the water tubes of a steam-generating water-wall of a boiler. Other hoods have a plurality of rectangular panels through which water flows and these panels are described more particularly in US. Pat. No. 3,347,539.

The panels described in this patent are characterized by a flat seamless faceplate in contact with the hot gases and a flat back-up plate arranged parallel to and only slightly spaced apart from the front faceplate. Between the two parallel plates area plurality of vanes that subdivide the space between the faceplate and back-up plates into long narrow water channels.

A water supply and a water collector box are usually located at opposite ends of the panel and the long edges of the plates are connected together by side walls.

A stress analysis of this form of panel indicates high combined stresses in the faceplate along the vanes where, due to internal water pressure, the bending moments are greatest. Also, the thermal expansions are obstructed at the vanes and the welding which connects the vanes to the front and back-up plates aggrevate the stress concentrations.

Due to the unfavorable conditions in which such panels function, the peaks of combined stresses result in permanent strains in the panel structure. The heat cycle is cyclic. That is, the front face is subjected to intense heat during the blowing period of the BOP and then the front face is cooled when the BOF is tilted to pour off the steel. Cyclic permanent strains usually result in cracks in the faceplate. The damage is usually hastened by non-uniform water flow distribution in the several flow channels of the panel.

In another form of water-cooled panel known from the prior art, a flat faceplate is associated with channels or angle irons welded side by side and to the faceplate to form internal'flow passages. Staybolts are used to reduce the length of unsupported front panel plate area and water inlet and outlet boxes,

with plenum chambers only, are attached to opposite ends of i the panel. Experience shows that these panels are less prone to cracking, however, excessive thermal deformation render this form of panel unsuitable for prolonged service.

It is characteristic of all hood panels that one surface-the surface that is contacted by the hot effluent gases and slag that is ejected upward into the hood during the blowing period-is subjected to intense heat periodically and the opposite surface of the panel is cooled by water flowing rapidly through the panel.

The flow velocity of the cooling water is high, and so only a small amount of heat is transferred to the water per unit length of panel.

In order to conserve water and to more effectively cool the panels, relatively narrow passages or conduits are provided in each panel and several panels are usually fluidly connected in series. Consequently, in hoods of this type, the water pressure drop is quite large. Water pressure, then, is greatest at the bottom of the hood in the lowermost panels where the converter gases, leaving the 801-, at about 3,000 F., are being mixed withair entering the hood.

Vehement combustion takes place there, resulting in very high temperatures. The heat load from the combustion is aggrevated by very hot, even molten slag and metallic particles, violently ejected from the molten bath of the furnace. These particles may adhere to and solidify on the panel surface, resulting in hot spots and excessive local thermal deformations.

The combined .actions of water pressures and thermal movements may lead to serious damages. Cracks could developand split the plate structure of the panels, and the leakages may become irreparable and render the panel un- SUMMARY OF .THE INVENTION The panel of the invention comprises an undulating, waveform like interior plate disposed in close proximity to an outer plate, and means connecting the perimetrical edges to form a hollow panel. A divider bar is disposed in the panel to form fluid-flow channels therein, and means is provided to introduce cooling fluid into and remove cooling fluid from the panel.

For a further understanding of the invention and for features and advantages thereof, reference may be made to the following description in conjunction with the drawings which illustrate, by way of an example, one embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a schematic side elevational view of an exhaust hood comprised of water-cooled panels in accordance with the invention;

FIG..2 is a side elevational view of .a typical panel. in the hood of FIG. 1;

FIG. 3 is a sectional view along line Ill-III of FIG. 2;

FIG. 4 is a sectionalview along line lV-IV of FIG. 3; and

FIG. 5 is asectional view, similar to that of FIG. 3, of a modified panel.

DETAILED DESCRIPTION FIG. 1 illustrates schematically an exhaust receiving hood l1 situated above a conventional BOF 12 that is comprised of a plurality of joined together water-cooled panels 13 that are arranged in separate tiers l5, l7, 19, 21. The tiers of panels are supported by a tubular water-carrying frame 23 which is not unlike that shown and described in U.S. Pat. No. 3,347,539.

A typical water-cooledpanel 13 (FIGS. 2 and 3) comprises an elongate backplate 25 and an undulating elongate front plate 27 which are disposed relatively close together. The undulations of the front plate show a regular rising and falling shape which is a wave-like form having crests 26 and troughs 28 that are regularly spaced across the width of the panel 13. At several locations, particularly at the troughs 28, where the undulating front plate 27 is closest to the flat back plate 25, there are elongate vane divider bars or plates 29 that are welded, as shown, to both the front plate 27 and to the back plate 25. These vane divider plates 29, 35 form internal fluid flow channels 30 within the panel 23.

The undulating front plate 27 is flanged over at the sides, as at 31, and is welded along the longitudinal edge as at 33 of the back plate 25 to close the sides of the panel 13.

Two of the vane divider plates 35 are disposed equidistant from the center line of the panel cross section and they extend some distanceoutward from the back plate 25, as shown in FIG. 3. These vane. divider plates 35 and the flangedsides 31 are effective as longitudinal stiffeners for the panel 13.

At strategic locations, about where shown in FIG. 2, there are lugs 37 that are welded to the flanged sides 31 and to the vane divider plates 35. On the lugs 37 are panel supporting pipes 39, and these supporting pipes cooperate with hooks (not shown) fixed to the supporting frame 23. Thus, a tier of panels is carried by the frame and the panels may be readily removed, repaired and replaced as necessary.

The ends of the panel 13 are closed by a water inlet header 4] and by a water collector outlet header 43. A water inlet nipple 45 is mounted to the water inlet header 41 for connection to a water supply conduit.

Within the water inlet header 4! the lower edge 47 of the back plate 25 is disposed close to the bottom of the header 4] and the bottom edge 47, as shown in FIG. 2, tapers upwardly from a low point adjacent the inlet nipple 45 toward the sides 31 of the panel 13. Thus, a Venturi sort of water passage 49 is formed within the inlet header and equalization of water flow velocities is effected between the water flow channels 30 in the panel 13.

FIG. illustrates a modified water cooled panel 51 which has an arcuate back plate 53, and an arcuate front undulating plate 55. The front plate 55 is flanged at the ends to form sides 57 of the panel, and the same internal 59 and outwardly extending 61 vane divider plates are provided.

The modified panel 51 also has lugs 63 an d support pipes 65 located as described previously with respect to the panel 15. In other respects, the panel 51 is similar to the panel 13.

Generally, the panel 51 forms a portion of an exhaust hood that has a circular cross section. Those skilled in the art will appreciate that the structure shown in FIG. 5 may be readily applied to exhaust hoods having an elliptical or other cross sectional form. In practice, it is desirable that the angle subtended by the panel 51 be no more than 30 and preferably less than 30. Because the hood in which the curved panels 51 would be used are large in diameter, the arcuate length of the panel 51 is not large and no unusual structural problems arise.

A feature of the present invention is that the front face of the panel which is exposed to the heat of the gases in the hood is undulated and is not flat. This arrangement is capable of withstanding higher water pressure that is required to move the cooling water through the channels of the panel with sufficient velocity.

A feature of the undulated type of panel described herein is that it permits free transverse thermal movements and resists excessive longitudinal bending forces that develop in service.

A feature of the undulated type of panel described herein is that they are suitable to form hoods having not only polygonal but also circular, elliptical and even irregular cross sectional shapes.

A feature of the panel of the present invention is the Venturi-like passages in the water inlet header which tends to equalize the water flow velocity in all of the flow channels in the panel.

A feature of the panel of the present invention is that the undulated structure reduces both the thermal and pressure stresses. Thus, thinner plates may be used, and thinner plates enhance heat transfer so that better cooling is effected and the overall weight of the panel is significantly less.

While the foregoing describes with a certain degree of particularlity a preferred embodiment of the invention by way of an example, it is understood that the invention is not so limited, but is defined by what is hereinafter claimed.

What is claimed is:

1. In a water-cooled exhaust collecting hood including a plurality of water-cooled panels interconnected structurally and fluidly, the improvement comprising:

a. a water-cooled panel characterized by i. a first plate ii. an undulating second plate disposed in close proximity to, but spaced apart from, said first plate;

iii. means connecting the perimetrical edges of said first and second plates to form a hollow panel;

iv. means disposed within said hollow panel subdividing the space therein into elongate fluid-flow channels;

v. means for flowing fluid into said panel;

vi. means for flowing fluid out of said panel; and

vii. means for supporting said panel adjacent other panels to form said hood.

2. The panel of claim 1 wherein:

a. said means for flowing fluid into said panel includes a hollow header fluidly communicating with each one of said fluid-flow channels; and wherein b. said means for flowing fluid out of said panel includes a hollow header fluidly communicating with each one of said fluid-flow channels.

3. The panel of claim 2 wherein:

a. said means that subdivides the space within said panel includes:

i. at least one divider bar secured to said first plate and to said undulating second plate at a location where said undulation is closest to said first plate.

4. In a water-cooled exhaust collecting hood including a plurality of water-cooled panels interconnected structurally and fluidly, the improvement comprising:

a. a fluid-cooled panel characterized by i. a first plate;

ii. an undulating second plate, having at least two crests and one trough, disposed in close proximity to, but spaced apart from, said first plate;

iii. means connecting the perimetrical edges of said first and second plates to form a hollow panel;

iv. a divider within said hollow panel connecting said first and second plates and disposed where said second plate is closest to said first plate, said divider providing fluidflow channels within said panel; and

v. means for flowing a cooling fluid into and out of said panel.

5. The panel of claim 4 including:

a. means for supporting said panel adjacent other panels to fonn said hood.

6. The panel of claim 4 wherein:

a. said means for flowing a cooling fluid includes i. a hollow first header, fluidly communicating with said panel, into which said cooling flows, and

ii. a hollow second header, fluidly communicating with said panel, from which said cooling fluid flows.

7. The panel of claim 6 wherein:

a. said second plate extends within at least one of said hollow headers and forms therewithin a narrow fluid-flow passage whereby said cooling fluid flowing in said passage tends to flow with equal velocity in said fluid-flow channels.

8. The panel of claim 6 including:

a. means for equalizing the velocity of fluid flowing in said fluid-flow channels.

9. In a water-cooled exhaust collecting hood including a plurality of water-cooled panels interconnected structurally and fluidly, the improvement comprising:

a. a fluid-cooled panel characterized by i. a first arcuate plate;

ii. an undulating second plate, having at least two crests and one trough disposed in close proximity to, but spaced apart from, said first plate;

iii. means connecting the perimetrical edges of said first and second plates to form a hollow panel;

iv. a divider within said hollow panel connecting said first and second plates and disposed where said second plate is closest to said first plate, said divider providing fluidflow channels within said panel; and

v. means for flowing a cooling fluid into and out of said panel.

10. The panel of claim 9 wherein:

a. said means for flowing a cooling fluid includes i. a hollow first header, fluidly communicating with said panel, into which said cooling flows, and

ii. a hollow second header, fluidly communicating with said panel, from which said cooling fluid flows.

11. The panel of claim 10 wherein:

a. said second plate extends within at least one of said hollow headers and forms therewithin a narrow fluid-flow plurality of water-cooled panels interconnecte and fluidly, the improvement comprising:

14. In a water-cooled exhaust collecting hood including a d structurally a. an undulating plate having at least two crests and one trough forming theinterior surface of each one of said planes; and

1). structure cooperating with said undulating plate and forming said panel. 

1. In a water-cooled exhaust collecting hood including a plurality of water-cooled panels intercOnnected structurally and fluidly, the improvement comprising: a. a water-cooled panel characterized by i. a first plate ii. an undulating second plate disposed in close proximity to, but spaced apart from, said first plate; iii. means connecting the perimetrical edges of said first and second plates to form a hollow panel; iv. means disposed within said hollow panel subdividing the space therein into elongate fluid-flow channels; v. means for flowing fluid into said panel; vi. means for flowing fluid out of said panel; and vii. means for supporting said panel adjacent other panels to form said hood.
 2. The panel of claim 1 wherein: a. said means for flowing fluid into said panel includes a hollow header fluidly communicating with each one of said fluid-flow channels; and wherein b. said means for flowing fluid out of said panel includes a hollow header fluidly communicating with each one of said fluid-flow channels.
 3. The panel of claim 2 wherein: a. said means that subdivides the space within said panel includes: i. at least one divider bar secured to said first plate and to said undulating second plate at a location where said undulation is closest to said first plate.
 4. In a water-cooled exhaust collecting hood including a plurality of water-cooled panels interconnected structurally and fluidly, the improvement comprising: a. a fluid-cooled panel characterized by i. a first plate; ii. an undulating second plate, having at least two crests and one trough, disposed in close proximity to, but spaced apart from, said first plate; iii. means connecting the perimetrical edges of said first and second plates to form a hollow panel; iv. a divider within said hollow panel connecting said first and second plates and disposed where said second plate is closest to said first plate, said divider providing fluid-flow channels within said panel; and v. means for flowing a cooling fluid into and out of said panel.
 5. The panel of claim 4 including: a. means for supporting said panel adjacent other panels to form said hood.
 6. The panel of claim 4 wherein: a. said means for flowing a cooling fluid includes i. a hollow first header, fluidly communicating with said panel, into which said cooling flows, and ii. a hollow second header, fluidly communicating with said panel, from which said cooling fluid flows.
 7. The panel of claim 6 wherein: a. said second plate extends within at least one of said hollow headers and forms therewithin a narrow fluid-flow passage whereby said cooling fluid flowing in said passage tends to flow with equal velocity in said fluid-flow channels.
 8. The panel of claim 6 including: a. means for equalizing the velocity of fluid flowing in said fluid-flow channels.
 9. In a water-cooled exhaust collecting hood including a plurality of water-cooled panels interconnected structurally and fluidly, the improvement comprising: a. a fluid-cooled panel characterized by i. a first arcuate plate; ii. an undulating second plate, having at least two crests and one trough disposed in close proximity to, but spaced apart from, said first plate; iii. means connecting the perimetrical edges of said first and second plates to form a hollow panel; iv. a divider within said hollow panel connecting said first and second plates and disposed where said second plate is closest to said first plate, said divider providing fluid-flow channels within said panel; and v. means for flowing a cooling fluid into and out of said panel.
 10. The panel of claim 9 wherein: a. said means for flowing a cooling fluid includes i. a hollow first header, fluidly communicating with said panel, into which said cooling flows, and ii. a hollow second header, fluidly communicating with said panel, from which said cooling fluid flows.
 11. The panel of claim 10 wherein: a. said second plate extends within at leAst one of said hollow headers and forms therewithin a narrow fluid-flow passage whereby said cooling fluid flowing in said passage tends to flow with equal velocity in said fluid-flow channels.
 12. The panel of claim 10 including: a. means for equalizing the velocity of fluid flowing in said fluid-flow channels.
 13. The panel of claim 9 including: a. means for supporting said panel adjacent other panels to form said hood with said arcuate plate facing the interior of said hood.
 14. In a water-cooled exhaust collecting hood including a plurality of water-cooled panels interconnected structurally and fluidly, the improvement comprising: a. an undulating plate having at least two crests and one trough forming the interior surface of each one of said planes; and b. structure cooperating with said undulating plate and forming said panel. 